1. Field of the Invention
The present invention relates to a page data processor rasterizing page data for generating output data and outputting the output data to an output unit such as an image setter, a plate recorder or a digital printing machine, a page data processing method and a program.
2. Description of the Background Art
In the field of printing/prepress, an image processor generally rasterizes page data described in a page description language (hereinafter abbreviated as “PDL”) represented by PostScript (registered trademark of Adobe Systems Inc., U.S.A.) or PDF (portable document format) for generating output data and outputs page contents expressed by the page data to a recording medium such as a film, a printing plate or a paper through an output unit such as an image setter, a plate writer or a digital printing machine.
In this case, the image processor first rasterizes the page data for generating the output data, and thereafter transfers the generated output data to the output unit. According to this processing, however, the output unit cannot perform output operation before receiving the output data from the image processor but must remain in a dead time to perform no operation, leading to a problem in improvement of the efficiency of printing/prepress steps.
To this end, there is an attempt of analyzing the page data and calculating the time required for rasterization processing for rasterizing the page data from that requiring a short rasterization processing time and generating output data thereby reducing the dead time of the output unit and prompting improvement of the efficiency of the printing/prepress steps.
In this case, however, the sequence of pages is disadvantageously disordered due to generation of the output data from the page data requiring the short rasterization processing time, although the dead time of the output unit can be reduced.
In another attempt, the dead time of the output unit is reduced by a technique, referred to as “on-the-fly system”, of sequentially transferring output data generated by rasterizing page data to the output unit.
According to this technique, however, it follows that transfer of the output data to the output unit is interrupted when the contents expressed by the page data are so complicated that a long time is required for generating output data by rasterization processing, disadvantageously leading to interruption of output processing, i.e., an output interrupting time.
Further, the output unit cannot operate immediately after starting but requires a preparatory time for transporting the recording medium to a recording part or warming up the recording part, and hence the dead time of the output unit must be reduced in consideration of the preparatory time.